Crude oil hauled from the ground in crude oil production is first stored without further treatment in storage vessels, i.e., in crude oil tanks of large volume and is held ready for distribution. The storage times of the oil in this kind of vessel is frequently sufficiently long for considerable sedimentation to occur, especially under extreme climatic conditions. The sedimentation speed and the composition of the sediments usually differ according to the origin of the oil. If such vessels are emptied and refilled several times without removing the sediments, a layer of sediments of a thickness of 1.5 m or more can be formed. The quantity of crude oil contained in this kind of sediment layer is considerable because this layer consists to a large extent of thickened oil and higher molecular substances such as, e.g., asphalt, paraffins or waxes. The sediments can, however, also be formed from lighter components of crude oil by means of thickening under the influence of heat. The sediments often have a jelly-like consistency and are nothing else than a heavy fraction of crude oil, the components of which are very mixable with crude oil or lighter components of crude oil or are soluble in these. The sediments, however, also contain foreign matter in form of, e.g., stones or pieces of metal, mostly rust.
For a long time, the sediments in crude oil containers as described above have been unwanted material which still today are removed in periodic cleaning processes from the vessels with suitable cleaning media, mostly aqueous solutions of detergents, is deposed of in more or less sensible manner or is destroyed. In the patent publication EP-160805, a method has been described with which this kind of sediment in crude oil containers or similar storage or transport vessels can be brought into a recyclable form. For this purpose, crude oil is injected into the sediment by means of rotating heads with nozzles which heads are introduced into the sediment. Thus, over a large area the sediment is swirled around and distributed in the liquid, is made to move, and is dissolved at least partly. It proves to be advantageous to match the activities of the individual nozzle heads to each other, such that due to opposite rotation, the vortices created by each nozzle head create currents.
From the named publication (EP-160805) it can be seen that the described method is rather complicated. The reason for this is the necessary use of rotating lances with which a region as large as possible is treated with injected oil and with which the vortices are to be achieved. Regarding the use of energy and in particular regarding the device and the method for assembling it, the whole thing is relatively costly. Means, i.e., drives, for rotating the lances are required. The diluting media, the fresh crude oil must be introduced through these same lances. For the desired forming of eddies, controlling means are required to control the direction of rotation of the lances. Furthermore, this type of rotating lance is complicated mechanically and thus subject to disturbances. If the combined rotation fails the forming of eddies also fails, which, however, is relatively insignificant due to the two-dimensional effect of the rotating nozzles. However, the required simultaneous triple function, i.e., rotating the heads with, e.g., pneumatic means, pumping and injecting the crude oil and controlling the nozzle heads is costly and rather disadvantageous concerning the process. In addition, the construction of rotating lances requires a relatively high precision because roller bearings and other elements requiring narrow tolerances, e.g., for fit are included in the device. This makes designing and manufacturing such devices relatively expensive.